1. Field of the Invention
This invention relates to an air-fuel adjusting device in an internal combustion engine in which fuel supplied from a main nozzle in the carburetor is injected by a separately provided, solenoid energized valve nozzle such that the air-fuel ratio in the mixture will be adjusted into the theoretical air-fuel ratio.
2. Description of the Prior Art
In order to purify exhaust gas released from vehicles, an attempt is first made to neutralize the NOx with a reducing catalyst and then to purify the CO and HC by mixing secondary air into the exhaust gas while using oxidative catalysts. Generally, a reducing catalyst demonstrates high exhaust gas-purifying efficiency when the air-fuel ratio in the mixture is close to the theoretical ratio, so that it is desirable that the air-fuel ratio be controlled accurately to stay close to the theoretical ratio. Also, if the air-fuel ratio in the mixture is controlled precisely to remain close to the theoretical ratio, it is possible to remove the pollutants of CO, HC and Nox at one time with the use of a single catalyst. There are proposed means for mechanically controlling the air-fuel ratio in the mixture to keep it close to the theoretical ratio, but there is a certain limitation to the precision of such control means. Also, the use of an electronic control type fuel injection system makes the entire mechanism complicated and costly.